with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve showed a single-peaked
structure with a duration of about 20 sec. The peak count rate
was ~3000 counts/sec (15-350 keV), at ~4 sec after the trigger.
The XRT began observing the field at 09:17:08.2 UT, 60.5 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
fading, uncatalogued X-ray source with an enhanced position: RA, Dec
146.7019, 54.0131 which is equivalent to:

RA(J2000) = 09h 46m 48.45s
Dec(J2000) = +54d 00' 47.0"

with an uncertainty of 2.2 arcseconds (radius, 90% containment). This
location is 30 arcseconds from the BAT onboard position, within the BAT
error circle. This position may be improved as more data are received;
the latest position is available at http://www.swift.ac.uk/sper.
A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density consistent with the Galactic value of 1.17
x 10^20 cm^-2 (Willingale et al. 2013).
The initial flux in the 2.5 s image was 1.01e-09 erg cm^-2 s^-1 (0.2-10
keV).
The prompt automatic UVOT analysis is not available at this time.
However, there appears to be no credible afterglow candidate in the
initial data.
Burst Advocate for this burst is J. L. Racusin (judith.racusin AT nasa.gov).
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/too.html.)

These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB. The source is located at RA, Dec
9:46:48.54, +54:0:46.4 (J2000, +/-0.5").
Further observations are planned.
We thank the staff of the Observatorio Astron=F3mico Nacional in San Pedro
M=E1rtir.

with an uncertainty of 1.8 arcsec (radius, 90% confidence).
This position may be improved as more data are received. The latest
position can be viewed at http://www.swift.ac.uk/xrt_positions. Position
enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans
et al. (2009, MNRAS, 397, 1177).
This circular was automatically generated, and is an official product of the
Swift-XRT team.

GCN Circular #19238
P. D'Avanzo (INAF-OAB), T.G.R. Roegiers (PSU), L.M. McCauley (PSU),
J.A. Kennea (PSU), P.A. Evans (U. Leicester), S.L. Gibson (U.
Leicester), J.P. Osborne (U. Leicester), V. D'Elia (ASDC), A. D'Ai
(INAF-IASFPA) and J.L. Racusin report on behalf of the Swift-XRT team:
We have analysed 6.0 ks of XRT data for GRB 160327A (Racusin et al. GCN
Circ. 19235), from 51 s to 22.1 ks after the BAT trigger. The data
comprise 7 s in Windowed Timing (WT) mode (taken while Swift was
slewing), with the remainder in Photon Counting (PC) mode. The enhanced
XRT position for this burst was given by Goad et al. (GCN Circ. 19237).
The light curve can be modelled with an initial power-law decay with an
index of alpha=2.53 (+0.14, -0.13), followed by a break at T+291 s to
an alpha of 0.59 (+/-0.06).
A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.97 (+0.15, -0.09). The
best-fitting absorption column is consistent with the Galactic value
of 1.2 x 10^20 cm^-2 (Willingale et al. 2013). The PC mode spectrum has
a photon index of 1.90 (+0.16, -0.15) and a best-fitting absorption
column of 4.2 (+3.5, -3.0) x 10^20 cm^-2. The counts to observed
(unabsorbed) 0.3-10 keV flux conversion factor deduced from this
spectrum is 3.4 x 10^-11 (3.7 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:

If the light curve continues to decay with a power-law decay index of
0.59, the count rate at T+24 hours will be 0.023 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 7.7 x
10^-13 (8.5 x 10^-13) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00680655.
This circular is an official product of the Swift-XRT team.

with an uncertainty of 1.0 arcmin, (radius, sys+stat,
90% containment). The partial coding was 82%.
BAT light curve shows a single peak starting around
T-10 sec, peaking around T+5 sec and ending around
T+22 sec. T90 (15-350 keV) is 28 +- 9 sec (estimated
error including systematics).
The time-averaged spectrum from T-6.30 to T+42.80 sec
is best fit by a simple power-law model. The power
law index of the time-averaged spectrum is 1.84 +- 0.11.
The fluence in the 15-150 keV band is
1.4 +- 0.1 x 10^-06 erg/cm2. The 1-sec peak photon flux
measured from T+4.14 sec in the 15-150 keV band
is 1.8 +- 0.2 ph/cm2/sec. All the quoted errors are at
the 90% confidence level.
The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/680655/BA/

GCN Circular #19241
E. Mazaeva (IKI), A. Volnova (IKI), E. Klunko (ISTP), I. Korobtsev
(ISTP), A. Pozanenko (IKI) report on behalf of larger GRB follow-up
collaboration:
We observed the field of the GRB 160327A (Racusin et al., GCN 19235)
with AZT-33IK telescope of Sayan observatory (Mondy) starting on March,
27 (UT) 13:48:49. We do not detect any source within enhanced Swift-XRT
position (Goad et al., GCN 19237). In particular we do not detect the
source reported in GCN 19236 and it could confirm the source (Zach
Golkhou et al., GCN 19236) is an afterglow of the GRB 160327A.
Preliminary photometry of the combined image is following

Photometry is based on nearby SDSS-DR9 stars, Lupton transformations
into R.

GCN Circular #19242
WeiKang Zheng and Alexei V. Filippenko (UC Berkeley) report
on behalf of the KAIT GRB team:
The 0.76-m Katzman Automatic Imaging Telescope (KAIT), located at
Lick Observatory, responded to Swift GRB 151027A (Racusin et al.,
GCN 19235) starting at 09:17:37 UT, 90 s after the burst under
fair condition. Observations were performed with an automatic
sequence in the clear (roughly R), V, and I filters, and the
exposure time was 20 s per image.
The afterglow reported by Zach et al. (GCN 19236) was not detected
in any of our single images, however, it is detected in the
co-added images in both clear and I band, except V band. We report
the follow detection magnitude or upper limit:

These magnitudes are in the AB system and are not corrected for
Galactic extinction
in the direction of the GRB. Compared to our previous night of observations
(Golkhou et al., GCN 19236), the source flux has decayed substantially in
all bands. The source r - i color changes from 2.1 +/- 0.1 to 0.6 +/-
0.3 between our first and the second night observations. The strong color
change suggests the possibility of contamination by the GRB host galaxy at
late-time.
We thank the staff of the Observatorio Astron=F3mico Nacional in San Pedro
M=E1rtir.

We also note the presence of two other sources within 2.5=E2=80=9D of the=
GRB=20
afterglow: The first one is located at 09:46:48.35, +54:00:47.8 and has a=
=20
magnitude of i(AB) =3D 23.76+/-0.11, and the second one is at 09:46:48.55=
,=20
+54:00:44.2 with a magnitude of i(AB) =3D 24.24+/-0.15. We suspect that=20
these sources may be contributing to the magnitudes given by Golkhou=20
et al. (GCN 19243), especially in the bluer bands.
Spectroscopy of the GRB afterglow and the first of the two other objects=20
was obtained by exposing 3x1200 s with grism R1000R, which covers=20
between 5100 and 10100 Angstrom. We detect a trace of the GRB=20
afterglow above 7300 AA, below which the emission drops abruptly. The=20
other object shows a continuum over the complete spectral range,=20
suggesting that this object is unrelated to the GRB. The afterglow=20
spectrum is indicative of a Lyman-alpha drop at a redshift between 4.90=20
and 5.01, with a most probable value at z =3D 4.99, although even lower=20
redshifts could not be discarded for unusually large Hydrogen column=20
densities. Due to the low S/N of the spectrum we are not able to confirm=20
any other absorption lines at this time.

GCN Circular #19246
I.A. Smith (Rice U.), N.R. Tanvir (U. of Leicester), and Y. Urata (NCU)
report:
We observed the location of GRB 160327A (Racusin et al., GCN Circ. 19235)
using the SCUBA-2 sub-millimeter continuum camera on the James Clerk
Maxwell Telescope. The observation started at 10:24 UT on 2016-03-27,
corresponding to 68 minutes after the burst trigger. Exposures totaling
1.0 hours were made in good weather conditions. No source was detected,
with the RMS background noise being 2.0 mJy/beam at 850 microns and
26.0 mJy/beam at 450 microns.
We thank Callie Matulonis and Iain Coulson for the prompt support of
these observations that were taken under project M16AP005.

These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB.
In addition to our first night observations (Golkhou, et al., GCN 19236),
which show the afterglow peaking and then fading, our observations on 28
March and 1 April confirm the fading of the afterglow. The above
photometric analysis, based on PSF fitting, may still suffer from modest
contamination between sources. More detailed analyses are under way.
We thank the staff of the Observatorio Astron=F3mico Nacional in San Pedro
M=E1rtir.